Firefighters help to extinguish a massive blaze at a vacant warehouse on January 23, 2013 in Chicago, Illinois. More than 200 firefighters battled a five-alarm fire as temperatures were in the single digits.

Firefighters help to extinguish a massive blaze at a vacant warehouse on January 23, 2013 in Chicago, Illinois. More than 200 firefighters battled a five-alarm fire as temperatures were in the single digits.

Firefighters work to extinguish a massive blaze at a vacant warehouse on January 23, 2013 in Chicago, Illinois. More than 200 firefighters battled a five-alarm fire as temperatures were in the single digits.

Firefighters work to extinguish a massive blaze at a vacant warehouse on January 23, 2013 in Chicago, Illinois. More than 200 firefighters battled a five-alarm fire as temperatures were in the single digits.

Firefighters help to extinguish a massive blaze at a vacant warehouse on January 23, 2013 in Chicago, Illinois. More than 200 firefighters battled a five-alarm fire as temperatures were in the single digits.

Firefighters help to extinguish a massive blaze at a vacant warehouse on January 23, 2013 in Chicago, Illinois. More than 200 firefighters battled a five-alarm fire as temperatures were in the single digits.

A firefighter helps to extinguish a massive blaze at a vacant warehouse on January 23, 2013 in Chicago, Illinois. More than 200 firefighters battled a five-alarm fire as temperatures were in the single digits.

A firefighter helps to extinguish a massive blaze at a vacant warehouse on January 23, 2013 in Chicago, Illinois. More than 200 firefighters battled a five-alarm fire as temperatures were in the single digits.

Firefighters work to extinguish a massive blaze at a vacant warehouse on January 23, 2013 in Chicago, Illinois. More than 200 firefighters battled a five-alarm fire as temperatures were in the single digits.

Firefighters work to extinguish a massive blaze at a vacant warehouse on January 23, 2013 in Chicago, Illinois. More than 200 firefighters battled a five-alarm fire as temperatures were in the single digits.

Firefighters work to extinguish a massive blaze at a vacant warehouse on January 23, 2013 in Chicago, Illinois. More than 200 firefighters battled a five-alarm fire as temperatures were in the single digits.

Firefighters work to extinguish a massive blaze at a vacant warehouse on January 23, 2013 in Chicago, Illinois. More than 200 firefighters battled a five-alarm fire as temperatures were in the single digits.

Firefighters work to extinguish a massive blaze at a vacant warehouse on January 23, 2013 in Chicago, Illinois. More than 200 firefighters battled a five-alarm fire as temperatures were in the single digits.

Firefighters work to extinguish a massive blaze at a vacant warehouse on January 23, 2013 in Chicago, Illinois. More than 200 firefighters battled a five-alarm fire as temperatures were in the single digits.

Firefighters work to extinguish a massive blaze at a vacant warehouse on January 23, 2013 in Chicago, Illinois. More than 200 firefighters battled a five-alarm fire as temperatures were in the single digits.

Firefighters work to extinguish a massive blaze at a vacant warehouse on January 23, 2013 in Chicago, Illinois. More than 200 firefighters battled a five-alarm fire as temperatures were in the single digits.

Firefighters work to extinguish a massive blaze at a vacant warehouse on January 23, 2013 in Chicago, Illinois. More than 200 firefighters battled a five-alarm fire as temperatures were in the single digits.

Firefighters work to extinguish a massive blaze at a vacant warehouse on January 23, 2013 in Chicago, Illinois. More than 200 firefighters battled a five-alarm fire as temperatures were in the single digits.

Firefighters work to extinguish a massive blaze at a vacant warehouse on January 23, 2013 in Chicago, Illinois. More than 200 firefighters battled a five-alarm fire as temperatures were in the single digits.

Firefighters work to extinguish a massive blaze at a vacant warehouse on January 23, 2013 in Chicago, Illinois. More than 200 firefighters battled a five-alarm fire as temperatures were in the single digits.

Firefighters work to extinguish a massive blaze at a vacant warehouse on January 23, 2013 in Chicago, Illinois. More than 200 firefighters battled a five-alarm fire as temperatures were in the single digits.

Firefighters work to extinguish a massive blaze at a vacant warehouse on January 23, 2013 in Chicago, Illinois. More than 200 firefighters battled a five-alarm fire as temperatures were in the single digits.

Firefighters work to extinguish a massive blaze at a vacant warehouse on January 23, 2013 in Chicago, Illinois. More than 200 firefighters battled a five-alarm fire as temperatures were in the single digits.

Firefighters work to extinguish a massive blaze at a vacant warehouse on January 23, 2013 in Chicago, Illinois. More than 200 firefighters battled a five-alarm fire as temperatures were in the single digits.

A truck is covered in ice as firefighters help to extinguish a massive blaze at a vacant warehouse on January 23, 2013 in Chicago, Illinois. More than 200 firefighters battled a five-alarm fire as temperatures were in the single digits.

A truck is covered in ice as firefighters help to extinguish a massive blaze at a vacant warehouse on January 23, 2013 in Chicago, Illinois. More than 200 firefighters battled a five-alarm fire as temperatures were in the single digits.

A truck and chemical drums are covered with ice as firefighters help to extinguish a massive blaze at a vacant warehouse on January 23, 2013 in Chicago, Illinois. More than 200 firefighters battled a five-alarm fire as temperatures were in the single digits.

A truck and chemical drums are covered with ice as firefighters help to extinguish a massive blaze at a vacant warehouse on January 23, 2013 in Chicago, Illinois. More than 200 firefighters battled a five-alarm fire as temperatures were in the single digits.

Firefighters help to extinguish a massive blaze at a vacant warehouse on January 23, 2013 in Chicago, Illinois. More than 200 firefighters battled a five-alarm fire as temperatures were in the single digits.

Firefighters help to extinguish a massive blaze at a vacant warehouse on January 23, 2013 in Chicago, Illinois. More than 200 firefighters battled a five-alarm fire as temperatures were in the single digits.